Dumortierite is a hard, opaque gemstone, usually a
dusty denim blue, though rarely violet or pink
(Violite). It is sometimes called "Blue Desert Lapis."
In fact, it is one of the stones used to substitute
for true Lapis and is often sold as "Lapis"! However,
it lacks the characteristic gold flakes of true Lapis
Lazuli. It is rapidly gaining popularity, probably
because it goes well with denim (and because it is a
much less expensive alternative to Lapis). It gets its
name from the French Paleontologist, Eugene Dumortier.
Dumortierite is commonly used as a semi
precious/ornamental stone, in the manufacture of
high-grade ceramics/porcelain and as mineral
specimens. Displaying a vitreous to dull luster, its
crystals are translucent to transparent with massive
specimens appearing nearly opaque. Having an uneven
fracture Dumortierite has a hardness of 7 - 8.5 and a
specific gravity of 3.3 - 3.4.
Massive quartz
colored blue by included Dumortierite crystals is
commonly referred to as Dumortierite quartz.
Dumortierite, a boro-silicate mineral, is made unusual
by its very attractive deep violet blue color.
Interestingly, Dumortierite is the most common
boro-silicate with the exception of the Tourmaline
Group.
While not used as a precious gemstone due to a lack of
clarity, it displays a bright coloring and good
hardness. Massive specimens are carved into cabochons,
beads, sculptures, eggs and spheres and in China it
has been used as a lapis lazuli imitation. While
Dumortierite can be misidentified as other ornamental
stones (i.e. sodalite, lazurite and lazulite), blue
sodalite is less dense and has whiter portions, while
lazurite and lazulite are not fibrous.
Dumortierite occurs in Beaunan, France as well as
Quartzite, La Paz County, Arizona; Colorado; Oreana,
Nevada; New York, New York and Alpine, San Diego
County and Los Angeles County, California, USA;
Magadanskaya, Siberia, Russia; India and Sahatany,
Madagascar. It has many associated minerals including
quartz, kyanite, sillimanite, staurolite, andalusite,
muscovite, lazulite and pyrophyllite.
